The Stapelia genus, native to the arid and semi-arid regions of Southern Africa, represents a group of stem succulents known colloquially as the Starfish Flower. These plants belong to the Dogbane family, Apocynaceae, a classification shared with milkweeds. They are cultivated worldwide, thriving in environments mimicking their dry, sun-drenched native habitats. The plant’s reputation is built not on conventional beauty, but on one of nature’s most peculiar reproductive strategies.
Defining the Starfish Flower
The vegetative structure of Stapelia is often confused with cacti due to its leafless, fleshy stems adapted for water storage. These stems are typically four-sided, segmented, and range from green to reddish-purple depending on sun exposure, forming dense, low-growing clumps. Unlike true cacti, they are spineless, although the edges of the stems feature small, soft teeth or tubercles.
The genus contains many species. Stapelia gigantea produces some of the largest flowers in the plant kingdom, reaching diameters up to 40 centimeters. Stapelia variegata is another common species, featuring smaller, intricately patterned flowers.
The Carrion Flower’s Deceptive Strategy
The flower of the Stapelia is designed to attract pollinators through mimicry of decaying matter. This strategy is known as sapromyiophily, or “carrion fly love,” and it exploits the reproductive drive of certain insects. The flowers exhibit a star-shaped corolla, often with a fleshy texture, mottled coloring of maroon and cream, and a covering of fine hairs that visually suggest rotting flesh.
Olfactory mimicry is achieved by releasing volatile organic compounds (VOCs) that chemically resemble those produced by putrefying animal tissue. Compounds such as dimethyl disulphide and dimethyl trisulphide are key components in this foul odor, which is often strongest on warm afternoons. Blow flies (Calliphoridae) and flesh flies (Sarcophagidae) are drawn to this scent, perceiving the flower as an ideal site to lay their eggs.
The flies land on the flower, searching for a suitable place for their larvae, and inadvertently become coated in pollen. The plant offers no nectar reward; the flies are simply tricked into transferring pollen from one bloom to the next. The complex structure of the flower’s reproductive organs, the pollinia, clips onto the insect’s legs or mouthparts, ensuring the pollen is carried successfully to the next flower visited.
Cultivating Stapelia at Home
Cultivating the Starfish Flower is relatively low-maintenance, as its care requirements align with its native, arid environment. Stapelia requires bright light to encourage robust stem growth and flowering, ideally receiving several hours of direct morning sun or bright indirect light. Excessive exposure to intense, midday sun can cause the stems to turn reddish-purple, which is a sign of sun stress.
The plant’s succulent nature demands a gritty, extremely well-draining potting medium, such as a specialized cactus or succulent mix, to prevent the stems from rotting. Watering should be sparse, allowing the soil to dry out completely between applications. During the cooler winter months, when the plant enters dormancy, watering should be reduced significantly or stopped entirely to prevent fungal diseases and stem collapse.
Propagation is easily achieved through stem cuttings during the active growing season in spring or summer. A healthy stem section is cut and allowed to lie in a cool, dry place for several days until the cut end forms a protective callus. Once calloused, the cutting can be planted in dry, well-draining soil, where it will develop new roots over the following weeks.